if you've got some cash (you're from the US, so 200$ should do it) just get a new monitor that has component inputs.
I did that a few months ago, it's a bit expensive (cost me 300€), but I can hook my laptops, 360, wii and PS3 (when someone lends me one) all at the same time. No adapters means no signal quality loss.

if you have a tight budget, a VGA box should do it, but you might get some problems sometimes

I'll add that not all TV tuner cards have a noticeable delay. It depends on both the card you get and the software you use. Unfortunately, there's often little way of knowing whether or not a card you get will be suitable for gaming beforehand. For example, the TV tuner card I bought a while back had roughly a second of delay out of the box, but using something like ChrisTV to bypass its hardware mpeg-2 encoding cut the delay to milliseconds without damaging the picture quality much (after setting up ffdshow filters and the like).

Then again, I will say that I've never found a TV tuner card that had what I'd consider enjoyable picture quality for gaming. Plenty are respectable for watching TV, but when you're looking for *quality* image, they tend to disappoint. I actually just bought a 650 dollar hdtv/monitor for this very reason, since I recently renewed my interest in console gaming. You could probably get a pure monitor with nice inputs for a third of that or less.